Re: [TLS] How to Validate Servers' Identities w/out reliable source of time

Peter Gutmann <> Fri, 05 October 2018 01:00 UTC

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From: Peter Gutmann <>
To: "Dr. Pala" <>, TLS WG <>
Thread-Topic: [TLS] How to Validate Servers' Identities w/out reliable source of time
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Date: Fri, 5 Oct 2018 01:00:04 +0000
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Subject: Re: [TLS] How to Validate Servers' Identities w/out reliable source of time
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Dr. Pala <> writes:

>In particular, the problem is that without a reliable (or trusted) source of
>Time information, devices can not reliably validate certificates (i.e., is
>the certificate even valid... ? is it expired ? is the revocation info fresh
>enough ?) and my question for the list is about best practices in the space.

It depends what your goal is.  Are you doing the validity checking because
some document says you need to, or because it's required for an actual
security goal?  You mention IoT, in a lot of embedded/SCADA there's little to
no checking done because the goal is as close to 100% uptime as achievable,
and shutting down because of an expired cert when everything else is operating
normally is a absolute no-no.

What security and non-security goals are you aiming for?